package FourArithmeticOperations;

/**
 * Created by dell on 2017/10/9.
 */
interface Stack<T>
    {
        public void push (T element);

        /**  Removes and returns the top element from this stack.

         *   @return T element removed from the top of the stack

         */
        public T pop();

        /**  Returns without removing the top element of this stack.

         *   @return T element on top of the stack

         */
        public T peek();

        /**  Returns true if this stack contains no elements.

         *   @return boolean whether or not this stack is empty

         */
        public boolean isEmpty();

        /**  Returns the number of elements in this stack.

         *   @return int number of elements in this stack

         */
        public int size();

        /**  Returns a string representation of this stack.

         *   @return String representation of this stack

         */
        public String toString();
    }
